Radionuclide brachytherapy source systems for application of beta radiation

Abstract

Radionuclide brachytherapy sources and systems for applying beta radiation to a target area, for example for maintaining functioning drainage blebs or functioning drainage holes in the eye, e.g., to reduce intraocular pressure (IOP) of an eye being treated for glaucoma. The systems herein provide a substantially uniform dose across a particular area, thereby providing appropriate radiation therapies.

What is claimed is: 
     
         1 . A radionuclide brachytherapy source (RBS) comprising:
 a. a capsule ( 210 ) having a distal surface ( 212 ), a proximal surface ( 211 ) opposite the distal surface ( 212 ), and a side wall ( 215 ); and   b. an active beta radioisotope material ( 220 ) in an annulus configuration encased in the capsule ( 210 ), the active beta radioisotope material ( 220 ) emits beta radiation through at least a portion of the distal surface ( 212 ) of the capsule ( 210 ).   
     
     
         2 . The RBS of  claim 1 , wherein the active beta radioisotope material ( 220 ) comprises Strontium-90 (Sr-90), Phosphorus-32 (P-32), Ruthenium 106 (Ru-106), Yttrium 90 (Y-90), Strontium-90 in secular equilibrium with Yttrium 90, an isotope of cesium, I-125, or a combination thereof. 
     
     
         3 . The RBS of  claim 1 , wherein the capsule is from 2 to 12 mm in diameter. 
     
     
         4 . The RBS of  claim 1 , wherein the capsule is 10.8 mm in diameter. 
     
     
         5 . The RBS of  claim 1 , wherein the RBS has an activity from 10 to 120 mCi, or from 3.7 to 4.4 GBq. 
     
     
         6 . The RBS  claim 1 , wherein the RBS emits a beta radiation from a treatment surface to a treatment volume, the treatment volume having a diameter of 8 mm; the RBS system has a dosimetry profile such that: all points across the diameter of the treatment volume at the treatment surface have a dose rate of 55-85 cGy/sec, all points across the diameter of the treatment volume at a depth of 0.6 mm have a dose rate of 45-55 cGy/sec, all points across the diameter of the treatment volume at a depth of 1 mm have a dose rate of 35-48 cGy/sec, and all points across the diameter of the treatment volume at a depth of 2 mm have a dose rate of 17-25 cGy/sec. 
     
     
         7 . The RBS of  claim 1  further comprising a forceps grip ( 230 ) protruding from the proximal surface ( 211 ) or recessed into the proximal surface ( 211 ) of the capsule that is engageable with a pair of prongs or forceps to allow the RBS to be picked up preferentially by the proximal surface ( 211 ). 
     
     
         8 . The RBS of  claim 1  further comprising a cap system ( 110 ) for housing the radionuclide brachytherapy source (RBS), the cap system ( 110 ) comprises an inner cavity ( 140 ) formed by a side wall ( 115 ) and a bottom surface ( 112 ) sealed to a bottom edge ( 115   c ) of the side wall ( 115 ) around its perimeter, the inner cavity ( 140 ) is for accepting the RBS, wherein a flattening filter ( 150 ) is disposed on the bottom surface ( 112 ) in the inner cavity ( 140 ), the flattening filter ( 150 ) reduces at least a portion of beta radiation emitted from an RBS thereby controlling an amount of beta radiation emitted from the bottom surface ( 112 ) of the cap system ( 110 ). 
     
     
         9 . The RBS of  claim 8 , wherein the flattening filter ( 150 ) is annular and has an inner diameter, an outer diameter, and a thickness, the thickness is measured from a flattening filter top surface to a flattening filter bottom surface. 
     
     
         10 . The RBS of  claim 8 , wherein the flattening filter is annular, dome shaped, disc-shaped, a flattened dome, a truncated pyramid, a truncated cone, or trapezoidal. 
     
     
         11 . The RBS of  claim 8 , wherein the flattening filter ( 150 ) is constructed from a combination of two or more materials having different densities, different thicknesses, or a combination thereof. 
     
     
         12 . The RBS of  claim 8 , wherein the side wall has a thickness such that only 3% of a prescription dose of an RBS can pass through. 
     
     
         13 . The RBS of  claim 8 , wherein the cap system provides emission of beta radiation through at least a portion of the bottom surface, said portion of the bottom surface being the active surface area (S). 
     
     
         14 . The cap system of  claim 13 , wherein the RBS has an activity of 110 mCi. 
     
     
         15 . The cap system of  claim 13 , wherein the cap system provides beta radiation to a treatment volume (T). 
     
     
         16 . The cap system  claim 15 , wherein doses at all points within T at a depth are within a 70%, an 80% isodose contour, 90% isodose contour, or 100% isodose contour, depth being measured from the bottom surface of the cap system. 
     
     
         17 . The cap system of  claim 16 , wherein the depth is from 0.15 to 0.25 mm. 
     
     
         18 . The cap system of  claim 15  wherein T is 8 mm in diameter, and doses at all points within T at a depth from 0.1 to 2 mm are at least 80% of a prescription dose of the RBS system. 
     
     
         19 . The cap system of  claim 15 , wherein T is 10 mm in diameter, and doses at all points within T at a depth from 0.1 to 2 mm are at least 80% of a prescription dose of the RBS system. 
     
     
         20 . The cap system of  claim 15 , wherein T is 8 mm in diameter, and doses at all points within T at a depth from 0.1 to 1 mm are at least 80% of a prescription dose of the RBS system. 
     
     
         21 . The cap system of  claim 15 , wherein T is 10 mm in diameter, and doses at all points within T at a depth from 0.1 to 1 mm are at least 80% of a prescription dose of the RBS system. 
     
     
         22 . An RBS system that emits a radiation field from a surface into a volume, the volume having a diameter of 8 mm and a depth of 2 mm, wherein points within the volume have a dose rate relative to a 100% maximum dose rate at the surface; wherein all points across a plane of the volume at a depth of 0.19 mm have a dose rate from 80%-100% relative to the 100% maximum dose; wherein all points across a plane of the volume at a depth of 0.67 mm have a dose rate from 60-75% relative to the 100% maximum dose; wherein all points across a plane of the volume at a depth of 0.94 mm have a dose rate from 40-60% relative to the 100% maximum dose; wherein all points across a plane of the volume at a depth of 1.99 mm have a dose rate from 25-35% relative to the 100% maximum dose.